1. Field of the Invention
The present invention relates to a starter for use in an automotive vehicle, the starter having a pinion-rotation-restricting member for engaging a pinion gear with a ring gear of an internal combustion engine.
2. Description of Related Art
An example of the starter of this kind is disclosed in JP-A-9-217672. In this starter, a pinion gear coupled to an output shaft of an electric motor by means of a helical spline is shifted toward a ring gear of an internal combustion engine while restricting rotation of the pinion gear. In this manner, the pinion gear engages with the ring gear of the engine, and the engine is cranked up by the electric motor. To reduce an impact generated at the engagement of the pinion gear with the ring gear, the motor is operated stepwise. That is, a small amount of current is supplied to the motor at the first step to thereby rotate a rotor at a low speed until the pinion gear engages with the ring gear. At the second step after the pinion gear engages with the ring gear, a full amount of current is supplied to the motor to crank up the engine. In other words, the motor rotates at a low speed until engagement between the pinion gear and the ring gear is established, and then the motor rotates at a full speed. This two-step operation is performed in response to a stroke of a plunger driven by a magnetic switch.
To perform the two-step operation without fail, it is necessary to make a spring-load of a member connecting the plunger to a member for restricting the pinion rotation larger than a magnetic force generated in the magnetic switch for driving the plunger. In the starter disclosed in JP-A-9-217672, the plunger and the restricting member are connected by a crank bar that has a resiliency in its rotational direction. Therefore, there is a possibility that the plunger is driven in a period after the pinion is restricted and before the pinion is fully engaged with the ring gear. If the plunger is driven in this period, the second step commences, thereby supplying full current to the motor. If this happens, the object of the two-step operation, i.e., reduction of the engagement impact, cannot be attained.